Research On Strain Tunable Optical Properties Of Flexible Plasmonics

Noble metal nanomaterials have several unique physical and chemical properties which are very different to the bulk materials,so they can be widely used on sensors,electronic and optical devices,biomedical equipment,catalysis and so on.As the fundamental theory of optical properties of nanoparticles,the localized surface plasmon resonance generated by free electrons on metallic surface under external electromagnetic field makes gold and silver nanomaterials have numbers of optical applications,especially on preparation of flexible optical devices by integrating large-scale nanostructures onto elastomeric substrates to obtain flexible plasmonic.This paper introduced the optical characteristics of noble metals and metallic nanoparticles,basic theory of surface plasmons and completed the following work.First,we introduced the principle of the finite difference time domain(FDTD)method and make simulations on single gold nanosphere,nanorod and nanocube to study the localized surface enhancement and scattering properties,it improves that the simulation results are consistent with theoretical models.Then we calculated the dimer nanoparticles systems to study the influence of separation and assembly method of nanostructures with different shapes on optical performance and electric field distribution,which is the theoretical basis on controlling plasmonic effect under strain.The integration of gold nanostructures with elastomeric substrates enables fabrication of flexible optic membrane.By controlling the interparticle separation distance with stretching,we can study the change models of plasmonic effect and SERS electromagnetic enhancement factor of tunable nanostructures by 3D FDTD method.Under stretching,the separation distance increased,thus the dominant plasmonic resonant peaks of flexible nanosphere,nanorod,and nanocube structures shifted to blue,and the enhancement factor decreased,they both followed a power-law function with the applied strain.Besides,the power exponent showed a strong shape dependence,where higher rates of blue shift and decrease were observed for nanocube structures than that for other structures because plasmonic coupling showed more obvious influence on nanocube.As a result,it is predictable for the relationship between plasmonic effect of different types nanostructures and strain under stretching.